How to create slanted edges and rounded handles for a tray?
I'd do it using a Mirror Modifier and a Solidify Modifier.

Create a quarter of the tray, with no thickness.
Add a Mirror Modifier and a Solidify Modifier
Tilt the handle using a 3D cursor as pivot (or proportional editing)
Tilt the sides just by moving upper vertices.

The solidify modifier keeps even thicknes for you, saving fiddling with vertices.